Referring to the FIGURE, first a stack ceramic capacitor 1 which is a representative example of a stack ceramic electronic component according to this invention will be described.
The stack ceramic capacitor 1 has a stack body 2 constituted of a plurality of stacked dielectric ceramic layers 3 and a plurality of internal electrodes 4 and 5 formed along the interfaces between the dielectric ceramic layers 3.
First and second external electrodes 8 and 9 are formed at positions different from each other on an outer surface of the stack body 2. In the stack ceramic capacitor 1 shown in the FIGURE, the first and second external electrodes 8 and 9 are formed respectively on end surfaces 6 and 7 of a stack body 5 that oppose each other. Among the internal electrodes 4 and 5, there are a plurality of first internal electrodes 4 that are electrically connected to the first external electrode 8 and a plurality of second internal electrodes 5 that are electrically connected to the second external electrode 9. These first and second internal electrodes 4 and 5 are alternately disposed relative to the stack direction. On the surface of the external electrodes 8 and 9, first plating layers 10, 11 and second plating layers 12, 13 are formed if needed.
Scale reduction in particular is required in stack ceramic capacitors. Therefore, in the manufacturing process, a technique of simultaneously firing after green sheets of dielectric ceramic and internal electrode layers are stacked. For the purpose of cost reduction, a base metal such as Ni is used in the internal electrodes of the stack ceramic capacitors.
In recent years, thickness reduction in internal electrodes has been keenly demanded as a thickness reduction in dielectric ceramic layers proceeded further. However, when the thicknesses of the internal electrodes are reduced, there is a problem in that the covering ratio of the internal electrodes tends to decrease due to the metal grains coming to have a spherical shape, thereby raising a need of firing at a lower temperature.
Due to the demands for various characteristics on stack ceramic electronic components, there has also arisen a need to use metals of various kinds such as Ag and Cu as a metal for the internal electrodes. Also due to such reasons, there has arisen a need to fire at a further lower temperature.
Because of the above considerations, a ceramic material capable of being fired at a low temperature and exhibiting excellent dielectric characteristics is demanded.
Patent Document 1 discloses a barium titanate series dielectric porcelain composition suitable for multi-layer substrates or stack ceramic capacitors and states that the composition can be fired at 1000° C. or lower.
Patent Document 2 discloses a barium titanate series dielectric porcelain composition suitable for stack ceramic substrates and states that the composition can be fired at 1000° C. or lower.